Showing papers on "Communications protocol published in 1999"

Adaptive protocols for information dissemination in wireless sensor networks

Abstract: In this paper, we present a family of adaptive protocols, called SPIN (Sensor Protocols for Information via Negotiation), that efficiently disseminates information among sensors in an energy-constrained wireless sensor network. Nodes running a SPIN communication protocol name their data using high-level data descriptors, called meta-data. They use meta-data negotiations to eliminate the transmission of redundant data throughout the network. In addition, SPIN nodes can base their communication decisions both upon application-specific knowledge of the data and upon knowledge of the resources that are available to them. This allows the sensors to efficiently distribute data given a limited energy supply. We simulate and analyze the performance of two specific SPIN protocols, comparing them to other possible approaches and a theoretically optimal protocol. We find that the SPIN protocols can deliver 60% more data for a given amount of energy than conventional approaches. We also find that, in terms of dissemination rate and energy usage, the SPlN protocols perform close to the theoretical optimum.

Minimum energy mobile wireless networks

Abstract: We describe a distributed position-based network protocol optimized for minimum energy consumption in mobile wireless networks that support peer-to-peer communications. Given any number of randomly deployed nodes over an area, we illustrate that a simple local optimization scheme executed at each node guarantees strong connectivity of the entire network and attains the global minimum energy solution for stationary networks. Due to its localized nature, this protocol proves to be self-reconfiguring and stays close to the minimum energy solution when applied to mobile networks. Simulation results are used to verify the performance of the protocol.

Agile network protocol for secure communications with assured system availability

Abstract: A plurality of computer nodes communicate using seemingly random Internet Protocol source and destination addresses. Data packets matching criteria defined by a moving window of valid addresses are accepted for further processing, while those that do not meet the criteria are quickly rejected. Improvements to the basic design include (1) a load balancer that distributes packets across different transmission paths according to transmission path quality; (2) a DNS proxy server that transparently creates a virtual private network in response to a domain name inquiry; (3) a large-to-small link bandwidth management feature that prevents denial-of-service attacks at system chokepoints; (4) a traffic limiter that regulates incoming packets by limiting the rate at which a transmitter can be synchronized with a receiver; and (5) a signaling synchronizer that allows a large number of nodes to communicate with a central node by partitioning the communication function between two separate entities.

Networked virtual environments: design and implementation

Abstract: 1. The Promises and Challenges of Networked Virtual Environments. What Is a Networked Virtual Environment? Graphics Engines and Displays. Control and Communication Devices. Processing Systems. Data Network. Challenges in Net-VE Design and Development. Network Bandwidth. Heterogeneity. Distributed Interaction. Real-Time System Design and Resource Management. Failure Management. Scalability. Deployment and Configuration. Conclusion. References. 2. The Origin of Networked Virtual Environments. Department of Defense Networked Virtual Environments. SIMNET. Distributed Interactive Simulation. Networked Games and Demos. SGI Flight and Dogfight. Doom. Other Games. Academic Networked Virtual Environments. NPSNET. PARADISE. DIVE. Brick Net. MR Toolkit Peer Package. Others. Conclusion. References. 3. A Networking Primer. Fundamentals of Data Transfer. Network Latency. Network Bandwidth. Network Reliability. Network Protocol. The BSD Sockets Architecture. Sockets and Ports. The Internet Protocol. Introducing the Internet Protocols for Net-Ves. Transmission Control Protocol. User Datagram Protocol. IP Broadcasting Using UDP. IP Multicasting. Selecting a Net-VE Protocol. Using TCP/IP. Using UDP/IP. Using IP Broadcasting. Using IP Multicasting. Conclusion. References. 4. Communication Architectures. Two Players on a LAN. Multiplayer Client-Server Systems. Multiplayer Client-Server, with Multiple-Server Architectures. Peer-to-Peer Architectures. Conclusion. References. 5. Managing Dynamic Shared State. The Consistency-Throughput Tradeoff. Maintaining Shared State Inside Centralized Repositories. Reducing Coupling through Frequent State Regeneration. Dead Reckoning of Shared State. Conclusion. References. 6. Systems Design. One Thread, Multiple Threads. Important Subsystems. Conclusion. References and Further Reading. 7. Resource Management for Scalability and Performance. An Information-Centric View of Resources. Optimizing the Communications Protocol. Controlling the Visibility of Data. Taking Advantage of Perceptual Limitations. Enhancing the System Architecture. Conclusion. References. 8. Internet Networked Virtual Environments. VRML-Based Virtual Environments. Virtual Reality Transfer Protocol. Internet Gaming. Conclusion. References. 9. Perspective and Predictions. Better Library Support. Toward a Better Internet. Research Frontiers. Past, Present, and Future. References. Appendix: Network Communication in C, C++, and Java. Using TCP/IP from C and C++. Managing Concurrent Connections in C and C++. Using TCP/IP from Java. Managing Concurrent Connections in Java. Using UDP/IP from C and C++. Using UDP/IP from Java. Broadcasting from C and C++. Broadcasting from Java. Multicasting from C and C++. Multicasting from Java. References. Index. 0201325578T04062001

Stability analysis of networked control systems

Abstract: We introduce a control network protocol, try-once-discard (TOD), for networked control systems (NCS), and provide, for the first time, an analytic proof of global exponential stability for both the new protocol and the commonly used statically scheduled access methods Controllers are designed without regarding the presence of the network in the feedback loop, so consequently many controller design techniques may be employed The performance of the new network protocol and the statically scheduled protocols are compared in simulations

Onion Routing for Anonymous and Private Internet Connections

Abstract: : Preserving privacy means not only hiding the content of messages, but also hiding who is talking to whom (traffic analysis). Much like a physical envelope, the simple application of cryptography within a packet-switched network hides the messages being sent, but can reveal who is talking to whom, and how often. Onion Routing is a general purpose infrastructure for private communication over a public network [8, 9, 4]. It provides anonymous connections that are strongly resistant to both eavesdropping and traffic analysis. The connections are bidirectional, near real-time, and can be used for both connection-based and connectionless traffic. Onion Routing interfaces with off the shelf software and systems through specialized proxies, making it easy to integrate into existing systems. Prototypes have been running since July 1997. As of this article's publication, the prototype network is processing more than 1 million Web connections per month from more than six thousand IP addresses in twenty countries and in all six main top level domains. [7]

Multi-transactional architecture

Abstract: An automated transaction machine network which supports multiple-destination transactions and a variety of communication protocols and/or message formats including standard and proprietary protocols and/or message formats. The automated transaction machine network includes a Super-ATM (Automatic/Automated Transaction Machine) which interfaces with a variety of peripherals: standard-ATM peripherals and/or sensors, and nonstandard ATM peripherals and/or sensors. The Super-ATM can process traditional ATM transactions, non-traditional ATM transactions, and Point-of-sale (POS) transactions.

Design considerations for distributed microsensor systems

Abstract: Wireless distributed microsensor systems will enable the reliable monitoring and control of a variety of applications that range from medical and home security to machine diagnosis, chemical/biological detection and other military applications. The sensors have to be designed in a highly integrated fashion, optimizing across all levels of system abstraction, with the goal of minimizing energy dissipation. This paper addresses some of the key design considerations for future microsensor systems including the network protocols required for collaborative sensing and information distribution, system partitioning considering computation and communication costs, low energy electronics, power system design and energy harvesting techniques.

System and method for multi-protocol communication in a computer network

Abstract: A system for multi-protocol communication in the computer network has a user interface layer with a common data structure to permit instant messaging communication with multiple service providers that each have different communication protocols. Message data and commands are transferred to a conversion platform layer using an application programming interface (API). Within the conversion platform layer, the data and commands transformed to conform with the messaging requirements and communication protocol of the different service providers. The conversion process is transparent to the user and permits instant messaging to recipients regardless of the recipient's service provider. Incoming messages received from a recipient are received by the conversion platform layer and converted from the messaging requirements and communication protocol of the recipient's service provider to the common data structure of the user interface. The system also permits a user to establish and display a contact list even though the individuals in the contact list may be subscribers to different service providers. When the user logs on to the various service providers, the contact list data for each service provider is provided to the user interface and converted for display to the user.

TCP and UDP performance over a wireless LAN

Abstract: We present a comprehensive set of measurements of a 2.4 GHz DSSS wireless LAN and analyze its behavior. We examine issues such as host and interface heterogeneity, bidirectional (TCP) traffic and error modeling, that have not been previously analyzed. We uncover multiple problems with TCP and UDP performance in this system. We investigate the causes of these problems (radio hardware, device drivers, network protocols) and discuss the effectiveness of proposed improvements.

Analysis of the Internet Key Exchange protocol using the NRL Protocol Analyzer

Abstract: We show how the NRL Protocol Analyzer, a special-purpose formal methods tool designed for the verification of cryptographic protocols, was used in the analysis of the Internet Key Exchange (IKE) protocol. We describe some of the challenges we faced in analyzing IKE, which specifies a set of closely related subprotocols, and we show how this led to a number of improvements to the Analyzer. We also describe the results of our analysis, which uncovered several ambiguities and omissions in the specification which would have made possible attacks on some implementations that conformed to the letter, if not necessarily the intentions, of the specifications.

A formal framework and evaluation method for network denial of service

Abstract: Denial of service is becoming a growing concern. As our systems communicate more and more with others that we know less and less, they become increasingly vulnerable to hostile intruders who may take advantage of the very protocols intended for the establishment and authentication of communication to tie up our resources and disable our servers. Since these attacks occur before parties are authenticated to each other we cannot rely upon enforcement of the appropriate access control policy to protect us. Instead we must build our defenses, as much as possible, into the protocols themselves. This paper shows how some principles that have already been used to make protocols more resistant to denial of service can be formalized, and indicates the ways in which existing cryptographic protocol analysis tools could be modified to operate within this formal framework.

IP services over Bluetooth: leading the way to a new mobility

Abstract: We present protocol concepts for an extension of IP for mobility issues in Bluetooth networks. The protocol is called BLUEPAC IP, where BLUEPAC stands for "BLUEtooth Public ACcess". "Public access" means access to various kinds of information in public areas, e.g. airplane, train, hotel room, department store, museum. Bluetooth will reside in low-cost chips that provide wireless communication up to OSI Layer 2. By the end of this year many mobile devices, e.g. notebooks, PDAs, cell phones, will contain Bluetooth chips as a cable replacement. But Bluetooth is move powerful: with a suitable network protocol that inherits all aspects of IP, it will be possible to provide IP services over Bluetooth. BLUEPAC IP takes IP as a basis and additionally includes functionalities of mobile IP and cellular IP for local IP address assignment, routing issues and handoff support.

Symbolic Verification of Communication Protocols with Infinite StateSpaces using QDDs

Abstract: We study the verification of properties of communication protocols modeled by a finite set of finite-state machines that communicate by exchanging messages via unbounded FIFO queues. It is well-known that most interesting verification problems, such as deadlock detection, are undecidable for this class of systems. However, in practice, these verification problems may very well turn out to be decidable for a subclass containing most “real” protocols. Motivated by this optimistic (and, we claim, realistic) observation, we present an algorithm that may construct a finite and exact representation of the state space of a communication protocol, even if this state space is infinite. Our algorithm performs a loop-first search in the state space of the protocol being analyzed. A loop-first search is a search technique that attempts to explore first the results of successive executions of loops in the protocol description (code). A new data structure named Queue-content Decision Diagram (QDD) is introduced for representing (possibly infinite) sets of queue-contents. Operations for manipulating QDDs during a loop-first search are presented. A loop-first search using QDDs has been implemented, and experiments on several communication protocols with infinite state spaces have been performed. For these examples, our tool completed its search, and produced a finite symbolic representation for these infinite state spaces.

Method and apparatus for distributing network traffic processing on a multiprocessor computer

Abstract: A system and method are provided for distributing or sharing the processing of network traffic (e.g., through a protocol stack on a host computer system) received at a multiprocessor computer system. A packet formatted according to one or more communication protocols is received from a network entity at a network interface circuit of a multiprocessor computer. A header portion of the packet is parsed to retrieve information stored in one or more protocol headers, such as source and destination identifiers or a virtual communication connection identifier. In one embodiment, a source identifier and a destination identifier are combined to form a flow key that is subjected to a hash function. The modulus of the result of the hash function over the number of processors in the multiprocessor computer is then calculated. In another embodiment a modulus operation is performed on the packet's virtual communication connection identifier. The result of the modulus operation identifies a processor to which the packet is submitted for processing.

A generic framework for parallelization of network simulations

Abstract: Discrete event simulation is widely used within the networking community for purposes such as demonstrating the validity of network protocols and architectures. Depending on the level of detail modeled within the simulation, the running time and memory requirements can be excessive. The goal of our research is to develop and demonstrate a practical, scalable approach to parallel and distributed simulation that will enable widespread reuse of sequential network simulation models and software. We focus on an approach to parallelization where an existing network simulator is used to build models of subnetworks that are composed to create simulations of larger networks. Changes to the original simulator care minimized, enabling the parallel simulator to easily track enhancements to the sequential version. We describe our lessons learned in applying this approach to the publicly available ns software package (McCanne and Floyd, 1997) and converting it to run in a parallel fashion on a network of workstations. This activity highlights a number of important problems, from the standpoint of how to parallelize an existing serial simulation model and achieving acceptable parallel performance.

A model, analysis, and protocol framework for soft state-based communication

Abstract: "Soft state" is an often cited yet vague concept in network protocol design in which two or more network entities intercommunicate in a loosely coupled, often anonymous fashion. Researchers often define this concept operationally (if at all) rather than analytically: a source of soft state transmits periodic "refresh messages" over a (lossy) communication channel to one or more receivers that maintain a copy of that state, which in turn "expires" if the periodic updates cease. Though a number of crucial Internet protocol building blocks are rooted in soft state-based designs --- e.g., RSVP refresh messages, PIM membership updates, various routing protocol updates, RTCP control messages, directory services like SAP, and so forth --- controversy is building as to whether the performance overhead of soft state refresh messages justify their qualitative benefit of enhanced system "robustness". We believe that this controversy has risen not from fundamental performance tradeoffs but rather from our lack of a comprehensive understanding of soft state. To better understand these tradeoffs, we propose herein a formal model for soft state communication based on a probabilistic delivery model with relaxed reliability. Using this model, we conduct queueing analysis and simulation to characterize the data consistency and performance tradeoffs under a range of workloads and network loss rates. We then extend our model with feedback and show, through simulation, that adding feedback dramatically improves data consistency (by up to 55%) without increasing network resource consumption. Our model not only provides a foundation for understanding soft state, but also induces a new fundamental transport protocol based on probabilistic delivery. Toward this end, we sketch our design of the "Soft State Transport Protocol" (SSTP), which enjoys the robustness of soft state while retaining the performance benefit of hard state protocols like TCP through its judicious use of feedback.

Method and apparatus for accelerating data through communication networks

Abstract: A method and apparatus for accelerating data transport through communication networks (e.g., the Internet) is taught. The data sources may include Internet web pages, electronic mails, computer files, digitized pictures, voice and video. The method combines smart content-based data compression schemes with intelligent routing to efficiently move information across a network. The apparatus works with existing communications protocols (e.g., TCP/IP, UDP, HTTP, SMTP and POP3) and fits transparently with Internet browsing applications.

WebDAV: a network protocol for remote collaborative authoring on the Web

Abstract: Collaborative authoring tools generate network effects, where each tool's value depends not just on the tool itself, but on the number of other people who also have compatible tools. We hypothesize that the best way to generate network effects and to add collaborative authoring capability to existing tools is to focus on the network protocol. This paper explores a protocol-centric approach to collaborative authoring by examining the requirements and functionality of the WebDAV protocol. Key features of the protocol are non-connection-oriented concurrency control, providing an upward migration path for existing non-collaborative applications, support for remote manipulation of the namespace of documents, and simultaneous satisfaction of a wide range of functional requirements.

Inspector for computed relevance messaging

Abstract: The invention disclosed herein enables a collection of computers and associated communications infrastructure to offer a new communications process which allows information providers to broadcast information to a population of information consumers. The information may be targeted to those consumers who have a precisely formulated need for the information. This targeting may be based on information which is inaccessible to other communications protocols. The targeting also includes a time element. Information can be brought to the attention of the consumer precisely when it has become applicable, which may occur immediately upon receipt of the message, but may also occur long after the message arrives. The communications process may operate without intruding on consumers who do not exhibit the precisely-specified need for the information, and it may operate without compromising the security or privacy of the consumers who participate.

A high-performance network intrusion detection system

Abstract: In this paper we present a new approach for network intrusion detection based on concise specifications that characterize normal and abnormal network packet sequences. Our specification language is geared for a robust network intrusion detection by enforcing a strict type discipline via a combination of static and dynamic type checking. Unlike most previous approaches in network intrusion detection, our approach can easily support new network protocols as information relating to the protocols are not hard-coded into the system. Instead, we simply add suitable type definitions in the specifications and define intrusion patterns on these types. We compile these specifications into a high-performance network intrusion detection system. Important components of our approach include efficient algorithms for pattern-matching and information aggregation on sequences of network packets. In particular, our techniques ensure that the matching time is insensitive to the number of patterns characterizing different network intrusions, and that the aggregation operations typically take constant time per packet. Our system participated in an intrusion detection evaluation organized by MIT Lincoln Labs, where our system demonstrated its effectiveness (96% detection rate on low-level network attacks) and performance (real-time detection at 500Mbps), while producing very few false positives (0.05 to 0.1 per attack).

Energy-conserving access protocols for identification networks

Abstract: A myriad of applications are emerging, in which energy conservation is a critical system parameter for communications. Radio frequency identification device (RFID) networks, smart cards, and even mobile computing devices, in general, need to conserve energy. In RFID systems, nodes are small battery-operated inexpensive devices with radio receiving/transmitting and processing capabilities, integrated into the size of an ID card or smaller. These identification devices are designed for extremely low-cost large-scale applications, such that the replacement of batteries is not feasible. This imposes a critical energy constraint on the communications (access) protocols used in these systems, so that the total time a node needs to be active for transmitting or receiving information should be minimized. Among existing protocols, classical random access protocols are not energy conserving, while deterministic protocols lead to unacceptable delays. This paper deals with designing communications protocols with energy constraint, in which the number of time slots in which tags need to be in the active state is minimized, while the access delay meets the applications constraints. We propose three classes of protocols which combine the fairness of random access protocols with low energy requirements.

Systems and methods for wireless communications

Abstract: Systems and methods including a wireless communications device that consists of a collection of one or more processing elements, optionally forming a computer cluster, that together carry out the functions necessary to exchange information over a plurality of wireless communications links, wherein the communication links may employ different communication protocols, respectively. The systems and methods combine two techniques: the use of multiple flexible processing elements, and a design in which each of the elements can carry out any part of the processing performed by the device, including without limitation the physical, MAC, link, network, transport, and presentation layer processing.

Method and apparatus for universal data exchange gateway

Abstract: A universal gateway that allows data to be transferred between one or more network protocols and one or more control protocols is described. The various protocols can coexist on the same physical network medium or on separate networks. The gateway also provides tunneling of network protocols through a selected protocol, and centralized control of network nodes. By using the gateway, end-users can mesh together traditionally standalone, incompatible, networks into a universally accessible, centrally administered, “super-network.” The gateway provides a centralized node database, support for legacy protocols, a rules engine, and an object-oriented class library interface. Configuration is simplified through automatic device discovery. The centralized node database is managed by an active server node. High reliability access to the centralized node database is enhanced by the system fault tolerance provided by standby server nodes. When used in connection with a power line network, the gateway provides the ability to distribute various types of data streams over the power line. Routing handlers provided by the gateway allow virtually any of the legacy data networking services such as TCP/IP to be routed over the power-line.

Method and device for selecting a reconfigurable communications protocol between and IC card and a terminal

Abstract: There is provided a method and device for selecting a communications protocol between an integrated circuit card and a terminal. The terminal supports at least two communications protocols, with one of the at least two communications protocols being a preferred communications protocol. The terminal transmits a reset to the integrated circuit card and receives an answer-to-reset from the integrated circuit card indicative of a first communications protocol. The terminal determines whether the first communications protocol matches the preferred communications protocol. If the first communications protocol does not match the preferred communications protocol, the terminal transmits another reset to the integrated circuit card and receives another answer-to-reset from the integrated circuit card indicatives of a second communications protocol. According to another aspect of the invention, the integrated circuit card has a processing unit and a memory coupled to the processing unit, the memory having stored therein a plurality of answers-to-reset, where each of the plurality of answers-to-reset is indicative of a communications protocol. The integrated circuit card transmits one of the plurality of answers-to-reset responsive to a reset and transmits another one of the plurality of answers-to-reset responsive to a subsequent reset.

Communication traffic circle system and method for performing packet conversion and routing between different packet formats including an instruction field

Abstract: A communication system which includes more efficient packet conversion and routing for improved performance and simplified operation. The communication system includes one or more inputs for receiving packet data and one or more outputs for providing packet data. In one embodiment, the present invention comprises a "traffic circle" architecture for routing packet data and converting between different packet formats. In this embodiment, the system includes a data bus configured in a ring or circle. A plurality of port adapters or protocol processors are coupled to the ring data bus or communication circle. Each of the port adapters are configurable for converting between different types of communication packet formats. In the preferred embodiment, each of the port adapters are operable to convert between one or more communication packet formats to/from a generic packet format. The common generic packet format is then provided on the circular bus for circulation on the communication traffic circle between respective ones of the port adapters. In a second embodiment, the present invention comprises a cross-bar switch communication channel. This system is designed to receive a plurality of communications channels comprising packet data. The communication system comprises a plurality of protocol converters or protocol processors for converting possibly differing communication protocols or differing packet formats to/from a common generic packet format. Each of the protocol converters are coupled to a single-sided cross-bar switch to transmit/receive data to/from other protocol converters. The single-sided cross-bar switch is operable for interconnecting the multiple communications paths between arbitrary pairs of communications ports. The system preferably includes arbitration and control logic for establishing and removing connection paths within the cross-bar switch. In the preferred embodiment, the single-sided cross-bar switch is configurable for different transmission paths for added flexibility.

Method for data communication between a vehicle and a remote terminal

Abstract: An apparatus and methods are provided for data communications associated with a vehicle. The apparatus preferably includes at least one electronic subsystem associated with the vehicle and a plurality of electrical conductors connected to the at least one electronic subsystem and associated with the vehicle. A vehicle data communications protocol converter is preferably connected to the plurality of electrical conductors for converting a first data communications protocol associated with data communications along the plurality of electrical conductors to a second data communications protocol such as a local-area infrared or an RF data communications protocol. The apparatus also preferably includes a transceiver connected to the data communications protocol converter for transmitting the second data communications protocol from the vehicle and receiving the data communications protocol from a remote data communications terminal or another portion of the vehicle.

Mixed strand spaces

Abstract: Strand space analysis is a method for stating and proving correctness properties for cryptographic protocols. In this paper we apply the same method to the related problem of mixed protocols, and show that a protocol can remain correct even when used in combination with a range of other protocols. We illustrate the method with the familiar Otway-Rees protocol. We identify a simple and easily verified characteristic of protocols, and show that the Otway-Rees protocol remains correct even when used in combination with other protocols that have this characteristic. We also illustrate this method on the Neuman-Stubblebine protocol. This protocol has two parts, an authentication protocol (I) in which a key distribution center creates and distributes a Kerberos-like key, and a reauthentication protocol (II) in which a client resubmits a ticket containing that key. The re-authentication protocol II is known to be flawed. We show that in the presence of protocol II, there are also attacks against protocol I. We then define a variant of protocol II, and prove an authentication property of I that holds even in combination with the modified II.

Communication protocol binding in a computer system for designing networks

Abstract: A computer-implemented method of designing a network includes the steps of populating a network design sheet on a computer display with an intelligent device object that represents a device object having physical attributes and logical attributes, selecting a communication protocol object representing a communication protocol having logical attributes, determining if the communication protocol object can be validly bound to the intelligent device object by comparing the logical attributes of each, and binding the communication protocol object to the intelligent device object on the network design sheet only if the binding is valid.

TCP/IP/PPP modem

Abstract: An Internet network protocol stack, along with special logic, is embedded with a modem, thereby enabling a modem to become Internet-ready. As a result, the modem offloads much of the network protocol processing from the main CPU and improves the overall performance of the communication system.